A chance encounter with an impoverished child forces Trixie to see an unfamiliar darker side of life. As Nonnatus House welcomes a new resident, Nurse Barbara Gilbert, Tom Hereward has a surprise romantic gesture in store for Trixie.

The Nonnatus team rallies to support first-time parents Marie and Tony Amos when Tony is arrested for gross indecency with another male. Elsewhere, as Poplar is gripped by an outbreak of dysentery, Trixie undertakes her first official church duty since her engagement to Tom.

The midwives face one of their busiest nights to date, whilst Sister Winifred concentrates her efforts on the prostitutes of Poplar. Elsewhere, cracks start to appear in Trixie and Tom Hereward's relationship.

Phyllis deals with a diabetic teenager who has fallen pregnant, Sister Mary Cynthia comes into contact with a group of Irish Travellers, and Patsy organizes a square dance to raise money for the Cubs' trip to Norfolk.

Trixie and Sister Mary Cynthia help a deaf-and-dumb woman, and Barbara has a baffling case. Meanwhile, Fred's daughter arrives from Birmingham and interferes with his and Violet's engagement, and Delia has a proposal for Patsy.

Festive cheer is in plentiful supply as Poplar readies itself for Christmas. An unexpected surprise for a grieving mother helps bring the Christmas magic home, while Nonnatus is rocked to the core when one of its own goes missing.

A outbreak of typhoid erupts, and suspicion over who the carrier could be threatens to break apart a closely knit family. Sister Winfred faces a personal dilemma when a local teacher is revealed to be pregnant by a married man. When the woman takes matters into her own hands, Sister Winifred is forced to consider the role her own prejudices may have played. Meanwhile, Barbara inadvertently agrees to go to dinner with Tom, but is wracked with worry about how Trixie will react.

Dr Turner is horrified to realise he may be partly to blame as the cause of the recent rise in birth deformities comes to light, and tries to prevent further cases. Sister Evangelina returns to work, but has clearly been affected badly by her stroke, and her health continues to deteriorate. A pregnant bride goes into labour during her wedding reception, while her mother is forced to come to terms with her grandchild being conceived out of wedlock.

The team reunite but all is not well when a change of management shakes up Nonnatus House.

Dr Turner helps the Mullucks cope with the stresses of caring for a disabled child as the terrible legacy of thalidomide becomes apparent and Nurse Crane faces an unexpected crisis.